Detection method and detection device

Abstract

A detection method including forming a complex by binding, to a target substance, a first substance immobilized to a metal particle with magnetism and a second substance labeled with a fluorescent material, moving the complex by applying a magnetic field, illuminating the complex during movement with excitation light of a predetermined wavelength, the excitation light causing the fluorescent material to emit fluorescence, the fluorescence being enhanced by localized surface plasmon resonance that is produced by the metal particle, capturing the enhanced fluorescence over time and obtaining two-dimensional images, and detecting the target substance in accordance with a light spot included in each of the two-dimensional images, the metal particle including an inner core made of a magnetic material and an outer shell covering the inner core, the outer shell being made of a nonmagnetic metal material that produces the localized surface plasmon resonance.

What is claimed is: 
     
         1 . A detection method comprising:
 forming a complex by binding, to a target substance, a first substance immobilized to a metal particle with magnetism and a second substance labeled with a fluorescent material;   moving the complex by applying a magnetic field;   illuminating the complex during movement with excitation light of a predetermined wavelength, the excitation light causing the fluorescent material to emit fluorescence, the fluorescence being enhanced by localized surface plasmon resonance that is produced by the metal particle;   capturing the enhanced fluorescence over time and obtaining two-dimensional images; and   detecting the target substance in accordance with a light spot included in each of the two-dimensional images,   the metal particle including an inner core made of a magnetic material and an outer shell covering the inner core, the outer shell being made of a nonmagnetic metal material that produces the localized surface plasmon resonance.   
     
     
         2 . The detection method according to  claim 1 , wherein the illuminating the complex with the excitation light includes illuminating a substrate capable of forming a near field induced by the excitation light with the excitation light, thereby the complex positioned near a surface of the substrate being illuminated with the near field induced by the excitation light. 
     
     
         3 . The detection method according to  claim 2 , wherein the applying the magnetic field includes:
 applying a first magnetic field, thereby the complex being attracted toward the surface of the substrate, and   applying a second magnetic field, thereby the complex attracted to the surface of the substrate moving along the surface of the substrate.   
     
     
         4 . The detection method according to  claim 1 , wherein the magnetic material contains a paramagnetic substance, and the nonmagnetic metal material contains a diamagnetic substance. 
     
     
         5 . The detection method according to  claim 1 , wherein the nonmagnetic metal material is gold, silver, aluminum, or an alloy containing, as a main component, one of gold, silver, and aluminum. 
     
     
         6 . A detection device comprising:
 a sample container containing a sample including a complex that is formed by binding, to a target substance, a first substance immobilized to a metal particle with magnetism and a second substance labeled with a fluorescent material;   a magnetic field applicator applying a magnetic field to the sample contained in the sample container, thereby the magnetic field moving the complex;   a light source illuminating the sample contained in the sample container with excitation light of a predetermined wavelength, the excitation light causing the fluorescent material to emit fluorescence, the fluorescence being enhanced by localized surface plasmon resonance that is produced by the metal particle;   an image captures capturing the enhanced fluorescence over time and obtaining two-dimensional images; and   a detector detecting the target substance in accordance with a light spot included in each of the two-dimensional images,   the metal particle including an inner core made of a magnetic material and an outer shell covering the inner core, the outer shell being made of a nonmagnetic metal material that produces the localized surface plasmon resonance.   
     
     
         7 . The detection device according to  claim 6 , wherein the sample container includes a substrate capable of forming a near field upon being illuminated with the excitation light, and
 the light source illuminates the substrate with the excitation light, thereby the complex positioned near a surface of the substrate being illuminated with the near field induced by the excitation light.   
     
     
         8 . The detection device according to  claim 7 , wherein the magnetic field applicator includes:
 a first magnetic field applicator applying a first magnetic field to the sample and attracting the complex toward the surface of the substrate, and   a second magnetic field applicator applying a second magnetic field to the sample and moving the complex along the surface of the substrate.   
     
     
         9 . The detection device according to  claim 6 , wherein the magnetic material contains a paramagnetic substance, and the nonmagnetic metal material contains a diamagnetic substance. 
     
     
         10 . The detection device according to  claim 6 , wherein the nonmagnetic metal material is gold, silver, aluminum, or an alloy containing, as a main component, one of gold, silver, and aluminum.